1. Field of the Invention
This invention relates to a round shaft chisel with a clamping sleeve, wherein the round shaft chisel has a chisel head and a chisel shaft, which is rotatably maintained in the clamping sleeve.
2. Discussion of Related Art
Round shaft chisels are employed, for example, in mining operations to mine minerals or coal, or also in road construction for shaping a line or for removing the cover of a road. In this case a number of round shaft chisels are mounted on a chain or drum and during movement of the latter are engaged with the material to be removed.
The round shaft chisels are advantageously arranged so they are rotatable around their linear axis and achieve an even wear of a chisel head which is fastened to their tip and is equipped with a hard alloy cutting tool. The linear axis of the round shaft chisel can be arranged at an obtuse angle with respect to the movement direction in order to let the occurring forces act primarily in the linear direction and to a lesser degree transversely to the linear axis and to reduce the danger of breaking.
Round shaft chisels can have a cylindrical shaft which, because of tilting forces occurring during its employment, has an inclination toward jamming, which hampers the rotating movement, or to one-sided wear of the shaft or of the bore receiving it.
A disk cutting tool with a chisel holder having an at least sectionally conical receiver, a round shaft chisel and a wear-protection sleeve for receiving the round shaft chisel is known from German Patent Reference DE 101 60 668 C2. The wear-protection sleeve is positioned between the round shaft chisel and the chisel holder. In this case the wear-protection sleeve extends with a section into the receiver and is releasably connected there with the chisel holder.
The section of the wear-protection sleeve extending into the receiver has a conical front end portion and a cylindrical rear end portion. The wear-protection sleeve rests with pre-stress against the cylindrical inner wall of the receiver. Rock dust entering the gap between the chisel holder and the rotating round shaft chisel can hinder rotation of the round shaft chisel and collect in this area. Uneven wear of the cutting tool attached to the round shaft chisel can thus be caused.
European Patent Reference EP 1 216 343 B1 describes an arrangement for the releasable fixation in place of a round shaft chisel in a chisel bushing. The chisel bushing is releasably fixed in a chisel holder. In this case, the chisel bushing has a conical exterior shape, which is inserted into a corresponding opening in the chisel holder.
During operation, the chisel bushing and the chisel holder are fixedly connected with each other and cannot move in relation to each other. A fluid connection is provided for detachment of the chisel bushing, through which fluid can be introduced under pressure between the chisel bushing and the chisel holder.
German Patent Reference DE 196 24 363 B4 describes a round shaft chisel with a receiver such as published in European Patent Reference EP 1 216 343 B1. Here, the movement of the round shaft chisel in the direction of its axis is also described, which can act on a water supply device for spraying the chisel with water, which can be released by a valve through the chisel.
European Patent Reference EP 1 000 721 B1, U.S. Patent Reference 2003/0015907 and European Patent Reference EP 1 163 424 B1 each respectively describe a chisel holder for a chisel with a cylindrical shaft, wherein a section of the chisel holder with a conical outer contour is inserted into a support block. For being secured against relative rotation, the chisel holder has a flat outer surface in a direction parallel with respect to its longitudinal axis. The penetration of removed material into the area of the conical outer contour is more difficult with a circumferential widening of the chisel holder. The chisel holder has a cross-sectional narrowing, which is used as a predetermined breaking point and, in case of an overload, protects the support block and further structural elements, such as a rotating drum to whose circumference the bearing blocks are affixed. The chisel shaft, and thus the chisel head, are rotatably seated in the chisel holder.